A representational drawing of a very basic water supply system of the prior art, for a typical home is shown in FIG. 1. This shows a standard two pipe plumbing system (28) that distributes cold water and hot water to various facilities, where they are required. Water from the local municipality is piped from the main (12) into the basement of the house, where it is connected to the plumbing system feed pipe (22) that then supplies cold water to various rooms throughout the house for such facilities as kitchen sinks, toilets, washbasins, bathtubs, showers and laundry tubs. Cold water may also be supplied to certain appliances inside the home, as well as to outside taps for such things as washing the car, watering the garden, or for filling a swimming pool.
Additionally, the cold water is supplied to a hot water tank (40), wherein the cold water is heated by means of energy derived from the consumption of either gas or electricity. This hot water is then also distributed to various rooms throughout the house for most of the facilities mentioned above: kitchen sinks, washbasins, bathtubs, showers and laundry tubs, as well as to certain appliances inside the home, but generally not to toilets or to outside taps.
Depending upon the geographical location of the home, the temperature of the cold water supplied from the main may be as low as 5° C. [40° F.] or as high as 15° C. [60° F.], but generally the temperature averages about 10° C. [50° F.].
One disadvantage with cold water pipes in the home is that during the summer months, when hot and humid air comes into contact with the cold water pipes, the dew point for the air is quickly reached causing condensation to form along the cold water pipes, which then results in the familiar drips and puddles that can be very annoying, and can also be very damaging to the surrounding areas in the home. In order to help overcome this problem, the cold water pipes are generally encased in thermal insulation with a vapor retarding outer jacket, to isolate the cold water pipes from the hot and humid air.
Toilets also have similar problems with the condensation that can form on the outsides of toilet tanks and toilet bowls that have been flushed using cold water. In an attempt to overcome this problem, most toilets nowadays are supplied with an insulating plastic liner that is fastened onto the inside walls and bottoms of the toilet tanks to help isolate the porcelain of the tanks from the cold water that is contained in them. Sometimes fabric coverings are also placed around the outside of the toilet tanks, but generally there is a direct contact between the porcelain of the toilet tank and the surrounding air.
There are several problems with the use of the plastic insulating liner in toilet tanks, however. The liner inside the tank is incomplete due to the accommodation of the inlet and outlet connections for the tank. Also, the liner does not prevent condensation from forming around the outside of the porcelain toilet bowl which is in direct contact with air that may be hot and humid, while at the same time the inside of the toilet bowl has direct contact with cold water that is replenished after each flush.
There are also other locations where condensation can result from cold water pipes, such as at the connections to fixtures or appliances, or in areas where it is either impractical or impossible to insulate the pipes. In any case, the present methods that are used to protect the interior of a home from the condensation that results from the distribution of cold water inside the home suffer from several problems including those outlined above, and they depend upon defensively trying to insulate every possible pipe, fixture or appliance that may contain cold water.
A second disadvantage with cold water pipes is that usually the temperature of the water is too cold for the average person to wash their hands or face with it, or to clean their teeth with it, and so the average person also typically turns on the hot water tap in addition to the cold water tap, usually waiting for the hot water to arrive in order to raise the faucet discharge water temperature to a comfortable level, before commencing to wash or to clean teeth. This results in an unnecessary usage of hot water, as well as a wastage of water while waiting for it to become temperate enough, and then afterwards leaving the hot water pipe full of hot water which then dissipates its heat energy into the surrounding areas. There are, of course, occasions when hot water is necessary, such as for a bath or a shower, but it is wasteful of heat energy if hot water is used every time when only temperate water is required.
A third disadvantage with cold water pipes is that they are also used to supply cold water directly into hot water tanks (40), where the average temperature of the cold water which may be, for example, approximately 10° C. [50° F.] has to be raised up to the temperature of hot water, which may be, for example, approximately 54° C. [130° F.]. This means that, on average, with all of the hot water used in a home, the temperature of the cold water first has to be raised by a relatively large amount, such as by 44° C. [80° F.] for the case described above, and that the heat needed for this has to be provided by the consumption of energy, such as gas energy or electrical energy. Such consumption of energy is both wasteful of resources, and can be costly to the consumer.
Many systems have been proposed in the past for heating cold water efficiently. For example, U.S. Pat. No. 4,909,045 discloses a unit for producing hot water. However, typically such systems have many moving parts, such as pumps, and are thus relatively complex. As a result such systems are relatively high maintenance and can sometimes consume substantial amounts of power for their operation.
There is a continuing need for an improved water heating system that is simple to maintain and operate and that consumes little energy in its operation.